Nothing came out.
Ah - you have to turn the nozzle! I did so, and a spray of methylene chloride splashed back off the window onto my hand and forehead (fortunately, I wear glasses).
I have never actually experienced chemical burns; now I know why they call it that. It was basically like a hundred little fire ants on my forehead. Luckily, my head fits well under the new kitchen faucet.
There was no permanent damage, except to my pride, which heals quickly. And yes, I found the rubber gloves with great alacrity, and followed the instructions from that point on.
Oh, the paint! Yeah, it stripped it pretty well. I want to strip it because the top layer, a white paint that's probably latex, peels right off the layer below, which is ... I don't know what it is. Probably lead, except it's in suspiciously good condition for paint that would have to be over thirty years old. It's just that I can't imagine this property having ever even heard a rumor of lead remediaton. Ha! It is to laugh!
But clearly I need to repaint the window frames, so it makes sense to me to get everything off them first that will come off easily. Besides, it was a good excuse to try out a new toy, even if it's just a chemical.